Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 302334

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
534 PM CST Mon Jan 30 2023

Issued at 210 PM CST Mon Jan 30 2023

Through Tuesday night...

A large center of high pressure encroaching from the northwest will
keep the short term forecast quiet, but awfully cold. The
persistent cold advection from said high has prevented
temperatures today from warming more than a few degrees from early
this morning, even in the northwest CWA where they`ve been gifted
with a fair amount of sunshine so far today. Early this
afternoon, the area is sitting in the upper single digits and
teens. However, a decent breeze out of the northwest is keeping
wind chills in the single digits below zero across most areas. The
aforementioned sunshine is slowly creeping across the CWA this
afternoon as a pesky stratus deck is taking its time sneaking out
of here. The southern CWA may not even see clearing until after
sundown. Nonetheless, the area should see mostly clear skies
through evening and night, aiding in the bitter cold conditions in
store for tonight and early tomorrow.

Temperatures around daybreak tomorrow are forecast in the single
digits south of I-80 down to the double digits below zero in spots
across the Rockford metro and surrounding areas. With the high
centering itself over northern Illinois tomorrow morning, winds
tonight into the morning should be very light, if not calm for
several hours over the northwest CWA. Therefore, wind chills
shouldn`t depart too far from actual temperatures. Minimum wind
chills are forecast to drop near -20 degrees in spots across the
northwest CWA. Opted out of a wind chill advisory for tonight
given the overall lack of wind and widespread wind chills expected
to be slightly warmer than advisory criteria.

Tomorrow will see similar temperatures to today with highs in the
teens. Wind chills through the better part of the day are expected
to be in the single digits on either side of 0. Modest warm air
advection in the return flow of the departing high will bring
slightly warmer conditions for tomorrow night. Lows will be in the
single digits to slightly below zero with wind chills as low as the
teens below zero.



Issued at 210 PM CST Mon Jan 30 2023

Wednesday through Monday...

Wednesday and Thursday look comparatively "milder" as we briefly
emerge into a warm advection regime on the backside of a departing
1030 mb arctic high. Southwesterly breezes look to develop on
Wednesday and with things generally looking pretty sunny,
insolation and developing WAA may help push our temperatures a bit
above the NBM offering of low 20s even with our newly-minted
snowpack across northern Illinois.

A reinforcing surge of notably colder temperatures will arrive
Thursday night into Friday as a 1040+ mb arctic high slides east
across the Upper Midwest. With this high center expected to remain
mainly to our north, we should maintain some decent
northerly/northwesterly winds into Friday, so depending on just
how cold we get, could be flirting with Wind Chill Advisory
criteria (wind chills -20 F or below) during the morning. Friday
looks pretty unpleasant into the daytime hours with a lingering
northerly breeze which will likely hold wind chills in the single
digits above zero. We briefly get into the right entrance region
of a very sharp jet streak that`s slated to nose across the UP of
Michigan and this likely will set off some loosely-organized
arcs of modest f-gen through the day. Soundings look quite dry
below about 800 mb in the wake of the front, so at this point it
seems like the only impact from all of this would be a gradual
increase in mid-level cloud cover.

Renewed thrust of cold temperatures will drive an increase in lake
effect snow showers on Friday. Prevailing wind direction should
focus most activity just east of the region and a good deal of dry
air aloft will likely cut down on LES production overall, but
still seems like a scenario worth carrying some slight chance PoPs
across parts of Porter and eventually Lake counties in NW Indiana.
Winds eventually shift out of the southeast Friday night which may
shove lingering LES into NE Illinois, but too far out to pinpoint
any of this in the gridded database.

Series of fast-moving disturbances will move across the region
over the weekend, driving another period of robust warm advection
which should pretty quickly dislodge this latest bout of cold.
Lots of variability across the guidance suite regarding degree of
moistening associated with the first shortwave Saturday night. Dry
forecast for now is the way to go, but note that there is a signal
for some light precip in ensemble guidance during this time frame.
Another disturbance--this one with a bit more jet support--may
arrive during the Monday - Tuesday period next week although
temperatures initially may be warm enough to support just plain
rain ahead of the cold front.



For the 00Z TAFs...

534 PM...No forecast concerns this period. Northwest winds around
10kts to start will diminish this evening and turn more westerly
by morning with speeds possibly back to 10kts Tuesday afternoon.
One mid deck has pushed southeast of the area with another mid
deck across southern IA that may spread across the area later
tonight, but confidence is low. cms


LM...Small Craft Advisory...IN nearshore waters until 3 AM Tuesday.



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